Despite being pursued for a long time, hydrogen production via water splitting is still a huge challenge mainly due to a lack of durable and efficient catalysts. Molybdenum phosphide （MOP） is theoretically capable o...Despite being pursued for a long time, hydrogen production via water splitting is still a huge challenge mainly due to a lack of durable and efficient catalysts. Molybdenum phosphide （MOP） is theoretically capable of efficient hydrogen evolution reaction （HER） catalysis, however, there is still room for further improvement in its performance. Herein, we propose a design for MoP with a P-rich outermost atomic layer for enhancing HER via complementary theoretical and experimental validation. The correlation of computational results suggests that the P-terminated surface of MoP plays a crucial role in determining its high-efficiency catalytic properties. We fabricated a P-rich outermost atomic layer of MoP nanoparticles by using N-doped porous carbon （MoP@NPCNFs） to capture more P on the surface of MoP and limit the growth of nanoparticles. Further, the as-prepared material can be directly employed as a self-supported electrocatalyst, and it exhibits remarkable electrocatalytic activity for HER in acidic media; it also reveals excellent long-term durability for up to 5,000 cycles with negligible loss of catalytic activity.展开更多
The mesoscale eddy is a typical mesoscale oceanic phenomenon that transfers ocean energy. The detection and extraction of mesoscale eddies is an important aspect of physical oceanography, and automatic mesoscale eddy ...The mesoscale eddy is a typical mesoscale oceanic phenomenon that transfers ocean energy. The detection and extraction of mesoscale eddies is an important aspect of physical oceanography, and automatic mesoscale eddy detection algorithms are the most fundamental tools for detecting and analyzing mesoscale eddies. The main data used in mesoscale eddy detection are sea level anomaly(SLA) data merged by multi-satellite altimeters' data.These data objectively describe the state of the sea surface height. The mesoscale eddy can be represented by a local equivalent region surrounded by an SLA closed contour, and the detection process requires the extraction of a stable closed contour structure from SLA maps. In consideration of the characteristics of mesoscale eddy detection based on SLA data, this paper proposes a new automatic mesoscale eddy detection algorithm based on clustering. The mesoscale eddy structure can be extracted by separating and filtering SLA data sets to separate a mesoscale eddy region and non-eddy region and then establishing relationships among eddy regions and mapping them on SLA maps. This paper overcomes the problem of the sensitivity of parameter setting that affects the traditional detection algorithm and does not require a sensitivity test. The proposed algorithm is thus more adaptable. An eddy discrimination mechanism is added to the algorithm to ensure the stability of the detected eddy structure and to improve the detection accuracy. On this basis, the paper selects the Northwest Pacific Ocean and the South China Sea to carry out a mesoscale eddy detection experiment. Experimental results show that the proposed algorithm is more efficient than the traditional algorithm and the results of the algorithm remain stable. The proposed algorithm detects not only stable single-core eddies but also stable multi-core eddy structures.展开更多
文摘Despite being pursued for a long time, hydrogen production via water splitting is still a huge challenge mainly due to a lack of durable and efficient catalysts. Molybdenum phosphide （MOP） is theoretically capable of efficient hydrogen evolution reaction （HER） catalysis, however, there is still room for further improvement in its performance. Herein, we propose a design for MoP with a P-rich outermost atomic layer for enhancing HER via complementary theoretical and experimental validation. The correlation of computational results suggests that the P-terminated surface of MoP plays a crucial role in determining its high-efficiency catalytic properties. We fabricated a P-rich outermost atomic layer of MoP nanoparticles by using N-doped porous carbon （MoP@NPCNFs） to capture more P on the surface of MoP and limit the growth of nanoparticles. Further, the as-prepared material can be directly employed as a self-supported electrocatalyst, and it exhibits remarkable electrocatalytic activity for HER in acidic media; it also reveals excellent long-term durability for up to 5,000 cycles with negligible loss of catalytic activity.
基金The National Key R&D Program of China under contract No.2016YFC1401800the National Natural Science Foundation of China under contract No.41576176the National Programme on Global Change and Air-Sea Interaction under contract Nos GASI-02-PAC-YGST2-04,GASI-02-IND-YGST2-04 and GASI-02-SCS-YGST2-04
文摘The mesoscale eddy is a typical mesoscale oceanic phenomenon that transfers ocean energy. The detection and extraction of mesoscale eddies is an important aspect of physical oceanography, and automatic mesoscale eddy detection algorithms are the most fundamental tools for detecting and analyzing mesoscale eddies. The main data used in mesoscale eddy detection are sea level anomaly(SLA) data merged by multi-satellite altimeters' data.These data objectively describe the state of the sea surface height. The mesoscale eddy can be represented by a local equivalent region surrounded by an SLA closed contour, and the detection process requires the extraction of a stable closed contour structure from SLA maps. In consideration of the characteristics of mesoscale eddy detection based on SLA data, this paper proposes a new automatic mesoscale eddy detection algorithm based on clustering. The mesoscale eddy structure can be extracted by separating and filtering SLA data sets to separate a mesoscale eddy region and non-eddy region and then establishing relationships among eddy regions and mapping them on SLA maps. This paper overcomes the problem of the sensitivity of parameter setting that affects the traditional detection algorithm and does not require a sensitivity test. The proposed algorithm is thus more adaptable. An eddy discrimination mechanism is added to the algorithm to ensure the stability of the detected eddy structure and to improve the detection accuracy. On this basis, the paper selects the Northwest Pacific Ocean and the South China Sea to carry out a mesoscale eddy detection experiment. Experimental results show that the proposed algorithm is more efficient than the traditional algorithm and the results of the algorithm remain stable. The proposed algorithm detects not only stable single-core eddies but also stable multi-core eddy structures.
